XML-Schema validation with libxml2
From NJH-Wiki
- Author
- Volker Grabsch
Example Code
This C code shows how to do XML-Schema validation with libxml2. It handles all errors by returning a negative value. You may want to call an error function instead, or throw an exception.
#include <libxml/parser.h>
#include <libxml/xmlschemas.h>
int is_valid(const xmlDocPtr doc, const char *schema_filename)
{
xmlDocPtr schema_doc = xmlReadFile(schema_filename, NULL, XML_PARSE_NONET);
if (schema_doc == NULL) {
/* the schema cannot be loaded or is not well-formed */
return -1;
}
xmlSchemaParserCtxtPtr parser_ctxt = xmlSchemaNewDocParserCtxt(schema_doc);
if (parser_ctxt == NULL) {
/* unable to create a parser context for the schema */
xmlFreeDoc(schema_doc);
return -2;
}
xmlSchemaPtr schema = xmlSchemaParse(parser_ctxt);
if (schema == NULL) {
/* the schema itself is not valid */
xmlSchemaFreeParserCtxt(parser_ctxt);
xmlFreeDoc(schema_doc);
return -3;
}
xmlSchemaValidCtxtPtr valid_ctxt = xmlSchemaNewValidCtxt(schema);
if (valid_ctxt == NULL) {
/* unable to create a validation context for the schema */
xmlSchemaFree(schema);
xmlSchemaFreeParserCtxt(parser_ctxt);
xmlFreeDoc(schema_doc);
return -4;
}
int is_valid = (xmlSchemaValidateDoc(valid_ctxt, doc) == 0);
xmlSchemaFreeValidCtxt(valid_ctxt);
xmlSchemaFree(schema);
xmlSchemaFreeParserCtxt(parser_ctxt);
xmlFreeDoc(schema_doc);
/* force the return value to be non-negative on success */
return is_valid ? 1 : 0;
}
